Device for indicating the locking state of a fifth wheel coupling and sensor arrangement

ABSTRACT

A device is described for indicating the locking state of a fifth wheel coupling and an arrangement of a first and a second sensor. According to the prior art, the first sensor is arranged on the underside of the locking latch and monitors the position of the kingpin in relation to the locking latch. A second sensor that is used is an inductive proximity switch that monitors a safety mechanism against loosening. In practice, this type of positioning of the first sensor has led to damage of the locking latch and the first sensor, while the signals of the second sensor were often false signals. Thus, the object of the invention is to provide a device for indicating the locking state, which maximizes operational availability and minimizes false signals. A further object of the invention is to optimize the arrangement of the first and the second sensor. These objects are attained by arranging the first sensor detecting the kingpin in the area of the locating hole and configuring the second sensor as a magnetically sensitive sensor that interacts with a magnet mounted on the operating lever. The two sensors are based on different mechanisms of action.

The invention relates to a device for indicating the locking state of afifth wheel coupling, comprising an evaluation unit to which a first anda second sensor are connected and a display unit which is connected withthe evaluation unit. The device further relates to an arrangement of afirst and a second sensor on a fifth wheel with which a kingpin in alocked state is engaged in a positive locking manner.

DE 198 20 139 A1 represents a generic prior art in this connection. Thisdocument describes a method and an arrangement for monitoring the properlocking and securing of a fifth wheel equipped with a locking mechanismand a safety mechanism. A first sensor is provided for monitoring thestate of the locking mechanism and a second sensor for directly orindirectly monitoring the state of the safety mechanism. The firstsensor is an inductive proximity switch and is intended to be mounted onthe underside of the locking latch and to monitor the position of thekingpin in relation to the locking latch. If the kingpin is driven intoo high, it rises above the locking latch, which increases the risk offalse detections. In practice, however, such a positioning of the firstsensor has proven to be a drawback because the locking latch must firstbe locked before the sensor can detect the position of the king pin inrelation to the locking latch. An incorrect positioning of the kingpinled to increased wear and damage to the locking latch and the firstsensor mounted thereon, since the locking latch, even during travel, issubject to substantial impact loading, which is also transmitted to thefirst sensor. Another weak point is the flexibly installed cables. Thesecond sensor is likewise an inductive proximity switch, which monitorsa locking mechanism that secures the safety mechanism against loosening.For this purpose, a tongue of the locking mechanism is monitored, whichis within the detection range of the sensor only as long as the lockingmechanism stays in a locked position in which the operating lever issecured by a cam. The essential drawback of the sensor arrangement ofthis second sensor is that there are frequent false alarms because themajor part of the fifth wheel is made of steel, and actuating theoperating lever changes the position of a plurality of other componentsin relation to the second sensor, which then trigger a false signal.

Thus, the object of the invention is to provide a device for indicatingthe locked state that maximizes operational availability and minimizesfalse signals.

A further object is to optimize the arrangement of the first and thesecond sensor.

These objects are attained by a device for indicating the locking stateof a fifth wheel coupling, comprising a locating hole for receiving akingpin, an operating lever which in a locked position can be fixed in aholding position, and an evaluation unit to which a first and a secondsensor are connected as well as a display unit connected to theevaluation unit. According to the invention, the first sensor isarranged in the area of the locating hole and detects the kingpin, whilethe second sensor is a magnetically sensitive sensor, which interactswith a magnet mounted to the operating lever, such that the two sensorsare based on different mechanisms of action.

Basing the two sensors on different mechanisms of action, e.g. aproximity switch and a magnetically sensitive sensor, minimizes thepossible mutual influences as well as the risks of failure.

With respect to the coupling states that can be indicated on the displayunit, two states occur in normal operation. In a first state, the firstsensor detects a kingpin and the second sensor confirms a lockedposition of the operating lever.

In a second state, the first sensor does not detect a kingpin and thesecond sensor signals an open position of the operating lever, i.e. thetractor is currently driving without a semi-trailer with the fifth wheelready for coupling.

If the operating lever is in its open position and the kingpin ispresent or the operating lever is in its closed position and the kingpinis not present, the display unit signals an error message to the driver.

Positioning the first sensor in the locating hole of the fifth wheel,preferably in an area opposite the locking latch, places the firstsensor in an area that is subject to little wear. During the couplingprocess, the tractor backs up against the stationary semi-trailer, whichfor coupling with the fifth wheel of the tractor is provided with akingpin having an upper collar, a middle section with a smaller diameterfor engaging with the locking latch of the fifth wheel and a lowercollar. The first sensor can now sense, for example, the lower collar ofthe kingpin, which is already in the locating hole without the lockinglatch being closed. If the kingpin is incorrectly positioned, the drivercan first make corrections while the fifth wheel is in its open positionuntil the first sensor detects that the kingpin is horizontally andvertically in its correct position.

The second sensor used is a magnetically sensitive sensor. Suitable are,for example, reed sensors or Hall-effect sensors, which interact with amagnet located at a corresponding point of the operating lever. Themagnet preferably moves in the direction of the fixed second sensor.Since no other magnets are normally present on the fifth wheel, falsesignals are minimized.

The display unit is preferably arranged in a driver's cab of a tractorof a semi-trailer. Based on such an arrangement of the display unit inthe driver's cab, the driver receives information on the position of thekingpin in relation to the fifth wheel or the position of the operatinglever in an area visible from the driver's seat. As a result, the driverdoes not need to leave the cab during coupling and uncoupling to getthis information. Furthermore, the position of the operating lever iscontinuously displayed for the driver during travel and, in particular,after prolonged breaks.

The further object is attained, firstly, by a first sensor mounted to afifth wheel with which a kingpin in a locked state is engaged in apositive locking manner. A coupling plate for receiving the king pin hasa complementary locating hole, and the kingpin has an upper collar, amiddle section with a reduced diameter for engaging with a locking latchand a lower collar. According to the invention, the first sensor isdisposed in the area of the locating hole below the coupling plate anddetects the kingpin. The essential advantages are fixed cables that arenot subject to continuous motion, reduced impact loading of the sensorand a reduced risk of false detections due to fixed installation.

Advantageously, the first sensor detects the lower collar of thekingpin. In the first place, the lower collar, unlike, for example, themiddle section with the reduced diameter, is subject to little wear, sothat the distance between the sensor and the lower collar remainsconstant even after a prolonged operating time. A further advantage ofdetecting the lower collar of the kingpin is that the first sensor canbe fixedly mounted in a protected area underneath the coupling plate ofthe fifth wheel.

Advantageously, the first sensor lies radially opposite of the lowercollar of the engaged kingpin. Thus, an incorrect positioning or theabsence of the kingpin can be detected in all three spatial directions.

Preferably, the first sensor is disposed in an area opposite the lockinglatch. During normal travel, the kingpin contacts the locking latch withits middle section with the reduced diameter, such that wear occurs inboth components after a prolonged time, and they may have to bereplaced. The area of the locating hole opposite the locking latchcontacts the kingpin only when the tractor backs up and is thereforesubject to little wear. The locking latch can therefore be replaced inthe same manner as before, without the first sensor having to be removedand subsequently reinstalled and recalibrated in a time-consumingprocess. A further advantage is that the sensor can detect the kingpinwithout prior actuation of the locking latch. As a result, if thekingpin is incorrectly positioned, the fifth wheel coupling and, inparticular, the locking latch are not actuated and are consequentlyprotected from damage.

Advantageously, the first sensor can be a proximity switch. Proximityswitches are defined as only inductively operating sensors. Suchproximity switches are inexpensive, technically mature and can interactwith ordinary components made of steel, such that a conventional kingpinmay be used.

The additional object is further attained by an arrangement of a secondsensor on a fifth wheel receiving a kingpin, on which a locking latchmounted underneath a coupling plate rotatably fixes the king pin. Thelocking latch can be brought into an open position or a locked positionvia a locking mechanism. This locking mechanism comprises an operatinglever, which in the locked position can be fixed in a holding position.The second sensor is mounted on the underside of the coupling plate todetect the holding position of the operating lever. According to theinvention, this second sensor is a magnetically sensitive sensor thatinteracts with a magnet attached to the operating lever.

In contrast to the aforementioned proximity switches, magneticallysensitive sensors are defined as reed sensors or Hall-effect sensors.Such sensors respond to the presence of a magnetic field and aretherefore comparatively insensitive to adjacent steel components thatchange their position.

In a special embodiment, the operating lever can comprise a pivotedlever and a handle lever laterally displaceable thereon and securing theoperating lever. The magnet is arranged on the handle lever.

Such an embodiment makes it possible to operate the fifth wheel—andconsequently to switch between an open and closed position—with onehand. In this case, the pivoted lever is secured mechanically in thesame manner as before, e.g. with a notch-like recess that engages with awall or a cam of the fifth wheel. To be able to swing out the pivotedlever and thereby to release the notch-like recess from the wall, thehandle lever must be laterally displaced relative to the pivoted lever,such that a magnet disposed on the handle lever changes its position inrelation to the second sensor and thereby influences the magneticallysensitive sensor.

Preferably, the magnet is mounted on the coupling-side end of theoperating lever, particularly preferably on the coupling-side end of thehandle lever. This arrangement makes it possible to mount the secondsensor in a protected location within the fifth wheel. Mounting thesensor to the above-described embodiment of a one-handed actuation ofthe fifth wheel furthermore has the advantage that the second sensorsimultaneously detects the lever mechanism and thus also the pivotedlever, such that any defect in the area of the pivoted lever is alsodetected.

Advantageously, the second sensor is fixed in relation to the couplingplate. As a result, the sensor itself, its connecting cables andsoldered connections are less subject to mechanical loading.

The invention will now be described in greater detail, by way ofexample, with reference to two drawing figures in which:

FIG. 1 is a longitudinal section of a fifth wheel with a kingpin and afirst sensor, and

FIG. 2 is a bottom view of a fifth wheel with a first and a secondsensor.

FIG. 1 is a longitudinal section of the central area of a fifth wheel 1with a kingpin 3 arranged in a locating hole 2 (cf. FIG. 2). The kingpin3 essentially has an upper collar 11, a middle section 12 with a reduceddiameter below that and a lower collar 14. For a positive lockingengagement of the kingpin 3 with the fifth wheel 1, a locking latch 13pivotably supported on the coupling plate 10 engages with the middlesection 12 of the kingpin 3.

The first sensor 6 is disposed radially to the engaged kingpin 3 in areinforcing rib 21 where it is protected. It contactlessly detects thelower collar 14 of the kingpin 3 and sends an electrical signal via thefirst sensor line 22 to the evaluation unit 5. In addition to this firstsensor line 22, a second sensor line 23 of the second sensor 7 (see FIG.2) is connected to the evaluation unit 5. A data line 24 extends fromthe evaluation unit to e.g. the driver's cab of a tractor (neither ofwhich is shown) where it is connected to a display unit 8.

FIG. 2 is a bottom view that shows the underside 17 of the couplingplate 10 and a locking mechanism 16 engaging therewith. The lockinglever 13 is in its locked position if a kingpin 3 is present. The firstsensor 6 is accommodated in the reinforcing rib 21 on the locating hole2 in an area 15 opposite the locking latch 13.

The locking latch 13 is moved between an open position and the depictedclosed position via a locking mechanism 16. This motion is triggered viathe operating lever 4, which protrudes from the fifth wheel 1, isconstructed in two parts and can be actuated with one hand.Specifically, the operating lever 4 comprises the pivoted lever 18 andthe handle lever 19, which is mounted thereto so as to be laterallydisplaceable. In the depicted extended position of the handle lever 19,there is sufficient room in the lever opening 25 so that the pivotedlever 18 can likewise be laterally displaced and fixed by hooking theprojection 26 behind the cam 27. When the handle lever 19 is released,it is pulled in the direction of the coupling-side end 20 of theoperating lever 4 by the handle lever tension spring 28 and fills thelever opening 25 almost completely, so that the operating lever 4 isadditionally secured.

The above-described safety device is now monitored by a magnet 9arranged on the coupling-side end 20 of the handle lever 19, whichinteracts with a second sensor 7 mounted on the underside 17 of thecoupling plate 10. In case of a material fracture in components of theoperating lever 4 or the cam 27, the handle lever 19 could migrateoutwardly and the locking latch 13 could open as a result of vibrations.In this case, the distance between the magnet 9 and the second sensor 7would increase as the handle lever 19 migrates, which would be signaledto the driver via the display unit 8.

List of Reference Numerals

-   1 fifth wheel-   2 locating hole-   3 kingpin-   4 operating lever-   5 evaluation unit-   6 first sensor-   7 second sensor-   8 display unit-   9 magnet-   10 coupling plate-   11 upper collar-   12 middle section-   13 locking latch-   14 lower collar-   15 area opposite the locking latch-   16 locking mechanism-   17 underside of coupling plate-   18 pivoted lever-   19 handle lever-   20 coupling-side end-   21 reinforcing rib-   22 first sensor line-   23 second sensor line-   24 data line-   25 lever opening-   26 projection-   27 cam-   28 handle lever tension spring

1-2. (canceled)
 3. An apparatus, comprising: an arrangement of a firstsensor on a fifth wheel with which a kingpin in a locked state can beengaged in a positive-locking manner, in which a coupling plate has acomplementary locating hole to receive the kingpin, and the kingpin hasan upper collar, a middle section with a reduced diameter for engagingwith a locking latch and a lower collar, wherein the first sensor isarranged in the area of the locating hole below the coupling plate andis adapted to detect the kingpin.
 4. The apparatus as claimed in claim3, wherein the first sensor detects the lower collar of the kingpin. 5.The apparatus as claimed in claim 3, wherein the first sensor isradially opposite the lower collar of the engaged kingpin.
 6. Theapparatus as claimed in claim 3, wherein the first sensor is arranged inan area opposite the locking latch.
 7. The apparatus as claimed in claim3, wherein the first sensor is a proximity switch.
 8. An apparatus,comprising: an arrangement of a second sensor on a fifth wheel adaptedto receive a kingpin, in which a locking latch arranged underneath acoupling plate rotatably fixes the kingpin, the locking latch can bebrought into an open position or a closed position via a lockingmechanism, the locking mechanism comprises an operating lever, which inthe locked position can be fixed in a holding position, and the secondsensor is mounted on the underside of the coupling plate for detectingthe holding position of the operating lever, wherein the second sensoris a magnetically sensitive sensor, which interacts with a magnetmounted on the operating lever.
 9. The apparatus as claimed in claim 8,in which the operating lever comprises a pivoted lever and a handlelever laterally displaceable thereon and securing the operating lever,wherein the magnet is arranged on the handle lever.
 10. The apparatus asclaimed in claim 8, wherein the magnet is mounted on the coupling-sideend of the operating lever.
 11. The apparatus as claimed in claim 8,wherein the second sensor is fixed in relation to the coupling plate.12. The apparatus as claimed in claim claim 4, wherein the first sensoris radially opposite the lower collar of the engaged kingpin.
 13. Theapparatus as claimed in claim 12, wherein the first sensor is arrangedin an area opposite the locking latch.
 14. The apparatus as claimed inclaim 13, wherein the first sensor is a proximity switch.
 15. Theapparatus as claimed in claim 9, wherein the magnet is mounted on thecoupling-side end of the operating lever.
 16. The apparatus as claimedin claim 15, wherein the second sensor is fixed in relation to thecoupling plate.